| One year of global TOPEX/POSEIDON (T/P) altimeter sea-level and correction data were analyzed to consider the effect on the statistics of altimeter range corrections due to: (1) seasonal variability, (2) removal of shallow water, (3) area and data-density weighting, and (4) separate consideration of the equatorial region. Seasonal analysis was done to provide a better understanding of the temporal behavior of the statistics. The effects of shallow water were removed since shallow water has different dynamics than deep water and could skew some results. Area and data-density weighting was performed to keep the disproportionate amount of data available at the turning latitude from biasing the results. Finally, the equatorial region was considered separately since equatorial conditions and dynamics are different than those at mid and high latitudes. It was determined that the statistics of each of the corrections was affected by one or more of these factors.; In an effort to compensate for the correlations of the corrections, the use of adaptive filtering techniques were explored as a possible alternative method for applying the environmental corrections to uncorrected sea surface height data. Two types of adaptive filters were used for this analysis: the adaptive predictor and the interference-cancelling filter. Several of these filters were arranged in series to apply each of the corrections sequentially. Multiple filter series were used, with the filter order varied slightly in each series so that those effects on the final results could be studied. The results obtained from this effort should prove valuable to those who use the environmental corrections in determining altimeter sea-level heights. |
